Giant iceberg reveals life from a century ago hidden beneath a block the size of Chicago

An enormous iceberg, roughly the size of Chicago, has separated from Antarctica. The event has revealed an underwater environment that was concealed for about a century.

Images from satellites confirm that a massive block of floating ice detached on January 19, 2025, creating a rare chance to observe newly exposed habitats.

Within days, scientists directed a remotely operated vehicle beneath the chilly surface to document the region’s hidden life.

A few days after the detachment, expedition co-chief scientist Patricia Esquete was on site with her colleagues to investigate the sudden loss of the ice shelf cover.

She is affiliated with the Centre for Environmental and Marine Studies (CESAM) and the Department of Biology (DBio) at the University of Aveiro, Portugal.

Uncovering a hidden environment

Beneath layers of floating glacier ice, life had adapted to darkness and cold. The newly revealed site shows a maze of sponges, anemones, and other marine life occupying the seafloor 755 feet (236 meters) below the surface.

Researchers guided the remotely operated vehicle, SuBastian, with acoustic systems, since GPS signals cannot penetrate thick ice. Despite those challenges, the craft documented thriving clusters of invertebrates and coral that have likely existed for many years.

Life in antarctic waters

This part of the Bellingshausen Sea has drawn attention since researchers discovered species such as icefish, giant sea spiders, and octopuses near exposed seabeds.

Each organism plays a key role in an ecosystem that operates with minimal light and scarce food.

Brittle stars have been seen climbing sponge surfaces at depths of around 705 feet (215 meters) in places where ice retreated years ago. This suggests that once the ice barrier is gone, new species quickly move into the space.

Sudden openings and new research

When a large iceberg detaches, as it did from Antarctica’s George VI Ice Shelf, previously covered areas become accessible to currents carrying organic particles.

These drifting nutrients can boost the growth of marine organisms that were once isolated under thick ice.

Scientists used sediment cores and sampling equipment to collect evidence of how these communities develop. Cores can reveal the past influx of organic matter, helping experts map out ecological shifts over the years.

Voices from the expedition

“We seized upon the moment, changed our expedition plan, and went for it so we could look at what was happening in the depths below. We didn’t expect to find such a beautiful, thriving ecosystem,” said Esquete. 

“Based on the size of the animals, the communities we observed have been there for decades, maybe even hundreds of years.”

Experts suggest the biodiversity they encountered requires further analysis to determine how organisms adapt to shifts in ice coverage. 

Challenges in sub-ice exploration

Operating ROVs under 495 feet (150 meters) of ice poses many risks, including potential entrapment. Navigation relies on acoustic signals and constant monitoring of environmental changes that could affect safety.

Teams must adapt their techniques to handle unpredictable ice shifts and extreme temperatures. Specialized sampling devices allow them to gather fragile organisms without harming local habitats.

Next steps for discovery

Co-leader of the expedition, Aleksandr Montelli from University College London, emphasized that comprehensive studies in these settings are still rare.

Researchers are eager to publish detailed findings that describe how marine life persists without normal light sources or stable nutrient supplies.

“Being right there when this iceberg calved from the ice shelf presented a rare scientific opportunity. Serendipitous moments are part of the excitement of research at sea – they offer the chance to be the first to witness the untouched beauty of our world,” stated Jyotika Virmani, executive director at Schmidt Ocean Institute.

Reflections on hidden communities

Ice-free sections of Antarctica continue to appear in certain areas, revealing complex webs of life that evolve under the most intense conditions. These hidden communities offer new perspectives on biodiversity and adaptation strategies that may hold lessons for scientists worldwide.

As the ice continues to shift, other previously inaccessible seafloor regions might open up for study. Each chance to explore a freshly exposed habitat can reveal species that would otherwise remain unknown.

Looking ahead

Future expeditions may focus on octopus populations and their breeding habits in frigid conditions. These cephalopods often display surprising adaptability in low temperatures and limited food supplies.

Antarctic investigations also provide clues about changes in ocean chemistry that affect marine life globally. Understanding how organisms thrive under shifting ice may reveal insights about climate impacts on ecosystems elsewhere.

Experts caution that accelerated ice losses could limit the window of time to study these emerging communities. Researchers hope to collaborate across nations to investigate newly opened habitats before conditions change once more.

Each new survey adds a piece to the puzzle of life beneath Antarctic ice shelves. There is much more to learn about these hidden frontiers and the organisms that flourish in them.

Details of this research are available in a press release from the Schmidt Ocean Institute.

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